Reality, for me, is what is true. The truth is whatever is in front of you, whatever is really happening. Whether you like it or not, it's raining now. "It shouldn't be raining" is just a thought. In reality, there is no such thing as a "should" or a "shouldn't." These are only thoughts that we impose onto reality. The mind is like a carpenter's level. When the bubble is off to one side -- "It shouldn't be raining" -- we can know that the mind is caught in its thinking. When the bubble is right in the middle -- "It's raining" -- we can know that the surface is level and the mind is accepting reality as it is. Without the "should" and "shouldn't," we can see reality as it is, and this leaves us free to act efficiently, clearly, and sanely.
-- Byron Katie, Loving What Is
The naive application of that is to go around thinking "I shouldn't be thinking about 'should' all the time! I should stop doing that! I'm not thinking like I should!".
Here's another installment of rationality quotes. The usual rules apply: